The present invention relates to an image capturing unit, which is adapted to be built in a tip portion of an electronic endoscope.
Generally, an image capturing unit of an electronic endoscope includes a solid-state image capturing element, an electrically insulated base to support the image capturing element, and a metallic housing to airtightly enclose the image capturing element and the insulated base therein. The image capturing unit further includes a plurality of connection lands that are arranged in vicinity to a rear end of the insulated base outside the housing and are connected to signal conductors thereat. Examples of such an image capturing unit are disclosed in Japanese Patent Provisional Publications Nos. 2003-100920 and HEI 10-74865.
As an inserted portion of a tip of the endoscope is adapted to be inserted into live bodies, the image capturing unit of the endoscope is required to be downsized by tenths of a millimeter to a minimum extent,
However, in the image capturing units disclosed in the above-referenced publications, in order to inhibit noises to signals from intruding from connecting points of the connection lands and the conductors, the rear-end portion of the image capturing unit is required to be shielded by a conductive cylinder, which is arranged to be spaced in a radial direction from the connection lands and the signal conductors.
Therefore, as shown in FIG. 10, a diameter of a cylindrical shield 92, which extends from a circumference of an insulated base 91, tends to be greater than a diameter of a housing 94 that surrounds a solid-state image capturing element 93, and the like. In such a configuration, as an entire image capturing unit becomes greater, it becomes difficult to use the image capturing unit in an endoscope with a considerably smaller diameter In exchange, other components of the image capturing unit, such as a light guide for illumination and channel tubes, are required to be downsized in diameters thereof. Therefore, functionalities of the endoscope may have been limited by the configuration.